Folding air filter assemblies

ABSTRACT

Collapsible filter assembly includes a filter medium element and a frame at least partially surrounding the filter medium element. The frame and filter media element are configured to vary in at least two dimensions by folding or unfolding. In at least on example, the filter medium element is rectangularly pleated or round pleated. Upon removal of the filter assembly from packaging and other restraints, the filter assembly may naturally expand with regard to footprint and volume, with some manual assistance being expected of a typical user in unfolding from an area-reduced configuration to an area-expanded configuration, and from a volumetrically reduced configuration to a volumetrically expanded configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Patent Cooperation TreatyApplication No. PCT/US19/55094 entitled Folding Air Filter Assembliesfiled on Oct. 8, 2019, which claims priority to U.S. Provisional PatentApplication No. 62/742,708 entitled Foldable Air Filter Assemblies filedon Oct. 8, 2018, the entire contents of both of which are incorporatedby reference herein.

TECHNICAL FIELD

The present disclosure relates to air filtration technologies; inparticular, the present disclosure relates to foldable air filterassemblies for reduced configurations for storage and shippingconvenience.

BACKGROUND

A typical home or business HVAC air-handling system requires periodic oroccasional replacement of air filters. Consumers are burdened eitherwith frequent trips to purchase replacement filters or with acquiringand storing a number of replacement filters. However, HVAC air filtersare generally large and somewhat fragile. Consumers are also burdenedwith finding appropriately sized replacement filters, and becauseair-handling systems have dimensions that vary from unit to unit andthere is no specific industry standardization in place. Indeed, successin finding the needed correct size replacement filter is not assured onany given trip to a brick-and-mortar retail location where filters arestocked on shelves and sold to consumers in the traditionalpoint-of-sale (POS) fashion.

Compromises are thus forced upon consumers, including, for example, theuse of filters that are bit small or large in one or both rectangulardimensions, and frustrated consumers even delay or neglect suggestedperiodic filter replacement. When air driven through an air-handlingsystem bypasses an improperly fitted filter, airborne matter is notoptimally trapped at the filter, which can permit the accumulation ofmatter on HVAC system components and cause or aggravate respiratoryproblems. When filter replacement schedules are missed, filter blockageby matter/particles accumulated in an old filter can increase systempower consumption and wear; it can also harbor microbial growth, whichcan adversely affect respiratory health. Further, the dimensions as wellas the delicate nature of traditional air filters pose some challenges.For example, consumers can find it difficult to handle and transportpurchased filters without causing damage to the product. Retailers faceadditional problems with storing/stocking large and fragile productssuch as replacement filters; retailers are further forced to makecritical calculations regarding stocking a range of filter sizes wherebythe shelf-space available for each filter size may be minimized.

Accordingly, opportunities exist for improvements that overcome theabove-noted shortcomings of the art.

SUMMARY

This summary is provided to introduce in a simplified form concepts thatare further described in the following detailed descriptions. Thissummary is not intended to identify key features or essential featuresof the claimed subject matter, nor is it to be construed as limiting thescope of the claimed subject matter.

In at least one embodiment, a collapsible air-filter assembly comprisesa filter medium element, and a frame at least partially surrounding thefilter medium element. The frame and filter medium element areconfigured to vary in at least one dimension by folding or unfolding.

According to one or more embodiments, the frame comprises a top shelland a bottom shell, and wherein the filter medium element is placedbetween the top shell and bottom shell.

According to one or more embodiments, the filter medium element isrectangular pleated.

According to one or more embodiments, the filter medium element istrapezoidal pleated.

According to one or more embodiments, the filter medium element ispleated, wherein the pleats are generally rounded.

According to one or more embodiments, in a configuration expanded byarea and volume, the filter medium element has rectangular channelsextending from end to end.

According to one or more embodiments, the assembly further comprisesedge treatments nestled with the filter medium element.

According to one or more embodiments, channel sidewalls unfold upwardfrom a flattened configuration to a standing configuration when theair-filter assembly is volumetrically expanded.

According to one or more embodiments, when twice folded in twodimensions, the air-filter assembly is halved in length and halved inwidth.

In at least one embodiment, a variable filter assembly comprises afilter medium element, and a frame at least partially surrounding thefilter medium element. The frame and filter media element are configuredto be reducible in at least one dimension via a non-planar action. Thefilter medium element is pleated.

According to one or more embodiments, the pleats are generallyrectangular.

According to one or more embodiments, the pleats are generallytrapezoidal.

According to one or more embodiments, the pleats are generally rounded.

According to one or more embodiments, edge treatments assist inexpansion of the pleats.

According to one or more embodiments, the variable filter assembly alsoincludes a scrim layer extending approximately parallel to a major planeof the filter medium element and contacting the filter medium element,wherein the scrim layer comprises a flat top layer and bottom layer.

According to one or more embodiments, the scrim layer is configured tohave a tensile and bending stiffness such that the pleats are encouragedto rebound to an original shape profile in an expanded configuration ofthe variable filter assembly.

According to one or more embodiments, the variable filter assemblyfurther includes a frame wrap surrounding edges of the frame.

According to one or more embodiments, the frame wrap is configured toseal the ends of a pleated portion of the filter.

According to one or more embodiments, the frame wrap is configured toreduce noise associated with the filter moving when airflow is turned onor off.

In at least one embodiment a collapsible air filter is provided. In acollapsed configuration, the collapsible air filter is reduced in thedimension predominantly parallel to the direction of air flow. In anexpanded configuration, the collapsible air filter is increased in thedimension predominantly parallel to the direction of air flow. Inswitching from the collapsed configuration to the expandedconfiguration, a series of pleats of a filter media of the collapsibleair filter is expanded thus increasing the effective filter mediavolume.

According to one or more embodiments, a perforated or otherwise opensheet of resilient material laminated to the filter media assists in theexpansion of the pleats.

BRIEF DESCRIPTION OF THE DRAWINGS

The previous summary and the following detailed descriptions are to beread in view of the drawings, which illustrate particular exemplaryembodiments and features as briefly described below. The summary anddetailed descriptions, however, are not limited to only thoseembodiments and features explicitly illustrated.

FIG. 1 is a perspective view of a collapsible filter assembly, accordingto at least one embodiment, in a reduced (i.e., collapsed) firstconfiguration as removed from product packaging, according to one ormore embodiments of the presently disclosed subject matter.

FIG. 2 is a perspective view of the collapsible filter assembly of FIG.1 unfolding in a first dimension, according to one or more embodimentsof the presently disclosed subject matter.

FIG. 3 is a perspective view of the collapsible filter assembly of FIG.1 once unfolded and thereby doubled in length and area relative to thefirst configuration, according to one or more embodiments of thepresently disclosed subject matter.

FIG. 4 is a perspective view of the collapsible filter assembly of FIG.1 unfolding in a second dimension, according to one or more embodimentsof the presently disclosed subject matter.

FIG. 5A is a perspective view of the collapsible filter assembly of FIG.1 twice unfolded and thereby doubled in length, doubled in width, andquadrupled in area relative to the first configuration, according to oneor more embodiments of the presently disclosed subject matter.

FIG. 5B is an expanded view of a corner portion of the collapsiblefilter assembly in the configuration of FIG. 5A, according to one ormore embodiments of the presently disclosed subject matter.

FIG. 6A is a perspective view of the collapsible filter assembly of FIG.1 further volume expanded by thickness relative to the configuration ofFIG. 5A, according to one or more embodiments of the presently disclosedsubject matter.

FIG. 6B is an expanded view of a corner portion of the collapsiblefilter assembly in the configuration of FIG. 6A, according to one ormore embodiments of the presently disclosed subject matter.

FIG. 7 is an exploded perspective view of the collapsible filterassembly of FIG. 1, according to one or more embodiments of thepresently disclosed subject matter.

FIG. 8 is a perspective view of a filter medium element having pleatswith a rounded shape that forms part of a collapsible filter assembly,according to one or more embodiments of the presently disclosed subjectmatter.

DETAILED DESCRIPTION

Below, the technical solutions in the examples of the present inventionare depicted clearly and comprehensively with reference to the figuresaccording to the examples of the present invention. Obviously, theexamples depicted here are merely some examples, but not all examples ofthe present invention. In general, the components in the examples of thepresent invention depicted and shown in the figures herein can bearranged and designed according to different configurations. Thus,detailed description of the examples of the present invention providedin the figures below are not intended to limit the scope of the presentinvention as claimed, but merely represent selected examples of thepresent invention. On the basis of the examples of the presentinvention, all of other examples that could be obtained by a personskilled in the art without using inventive efforts will fall within thescope of protection of the present invention.

Any dimensions expressed or implied in the drawings and thesedescriptions are provided for exemplary purposes. Thus, not allembodiments within the scope of the drawings and these descriptions aremade according to such exemplary dimensions. The drawings are not madenecessarily to scale. Thus, not all embodiments within the scope of thedrawings and these descriptions are made according to the apparent scaleof the drawings with regard to relative dimensions in the drawings.However, for each drawing, at least one embodiment is made according tothe apparent relative scale of the drawing.

Unless described or implied as exclusive alternatives, featuresthroughout the drawings and descriptions should be taken as cumulative,such that features expressly associated with some particular embodimentscan be combined with other embodiments.

FIGS. 1-5A illustrate a collapsible filter assembly 100, according to atleast one embodiment, unfolding in ordered stages from an area-reducedconfiguration in which its footprint is most reduced (as illustrated,for example, in FIG. 1), to an area-expanded configuration (asillustrated, for example, in FIG. 5A), in which its footprint is mostexpanded. To prepare the collapsible filter assembly 100 for use, atypical user may remove the filter assembly 100 from product packaging102 in the area-reduced configuration of FIG. 1, which is preferable forstorage and shipping purposes due to the reduced footprint and/orvolume. Once removed from the product packaging 102, the collapsiblefilter assembly 100 is expandable to the area-expanded configuration ofFIG. 5A.

The collapsible filter assembly 100 further expands volumetrically asshown in FIGS. 6A-6B, which illustrate a sixth configuration of thefilter assembly 100, which is preferable for typical use as an airfilter. As the collapsible filter assembly 100 ultimately has somedegree of material flexibility and deformation, particularly when airflow pressures are applied, its operational configuration may be foundas somewhat flexed, bulged, or compressed relative to the depictions inthe drawings. Nonetheless, the collapsible filter assembly 100 can bedescribed as assuming an approximately planar configuration in the fullyexpanded configuration of FIG. 6A.

The footprint of the collapsible filter assembly 100 is understood asthe area, which can be determined, for example, by multiplication of thelength L and width W of the filter assembly 100. The footprint of thefilter assembly 100 in the drawings is rectangular, and can vary indimensions. Although the length L and width W are only particularlylabeled in the drawings in FIG. 6A, the footprint or area of the filterassembly has an effective lesser area in any of the configurations ofFIGS. 1 and 3, for example. The length L and width W are taken in thefilter plane, which is generally the plane perpendicular to thedirection in which air will flow when the filter assembly is expandedand in use, such that the air flows 50 (FIG. 6A) are directedapproximately parallel to the normal axis 104 of the filter plane. Thenormal axis 104 is understood as orthogonal to the length L and width Wdimensions, and the thickness T of the filter assembly is understood astaken along the normal axis 104. The volume of the collapsible filterassembly 100 is understood as approximately the multiplicative productof the length L, width W, and thickness T. In normal use, the air flows50 pass through the thickness T of the filter assembly FIG. 6A withinthe fully expanded area of the filter assembly as shown in FIG. 6A.

In transitioning from a packaged configuration (as shown, for example,in FIG. 1) to a configuration as ready for use (as shown, for example,in FIG. 6A), the collapsible filter assembly is unfolded alongengineered fold lines defined along one or more dimensions, such thateach fold during the unfolding process successively increases thefootprint. Accordingly, during the collapsing process, for exampleduring the manufacturing of the collapsible filter assembly, thecollapsing filter assembly is folded along the engineered fold linessuch that each fold during the folding process successively decreasesthe footprint.

The engineered fold lines can be rendered, for example, by thinning orstamping the material, embossing the material, perforating the material,and/or by adding a hinging structure, feature, or material. Thequarter-area-reduced configuration of FIG. 1 can be described as a twicefolded configuration having folds in two dimensions relative to thearea-expanded configuration of FIG. 5A. Similarly, thefractionally-reduced-area configuration of FIG. 3 can be described as aonce folded configuration having a fold in one dimension relative to thearea-expanded configuration of FIG. 5A.

The illustrated embodiment of the filter assembly 100 is designed to betwice folded, with one-fold each in two dimensions. In otherembodiments, the filter assembly is configured such that it can befolded three or more times. For example, at least one filter assembly isdesigned to be folded once in one of the two dimensions (i.e., L and W),and folded twice in the other of the two dimensions. For example, an airfilter assembly having an expanded footprint of dimensions 24 by 30inches, can be folded three times to have a reduced footprint ofapproximate dimensions 10 by 12 inches. Accordingly, a filter assemblyaccording to these descriptions can be folded once or any number oftimes.

In various embodiments, transitioning of the collapsed filter assemblyfor use can also include permitting the collapsible filter assembly toexpand in thickness, for example, as shown in transitioning from theconfiguration of FIGS. 5A-5B to the configuration of FIGS. 6A-6B. Theillustrated embodiment of the filter assembly is particularlyadvantageous in that regard, with a rectangular or trapezoidal pleatedfilter medium element 110 and edge treatments 120 as further describedbelow with reference to FIG. 7. In this particular example the filterassembly 100 has approximately rectangular shaped channels 112 (see FIG.7) terminating at opposing ends. This design facilitates the top side106 of the filter assembly 100 rocking upward as internal channel walls114 unfold upward from a flattened configuration (FIG. 5B) to standingconfiguration (FIG. 6B). The pleated filter medium and edge treatmentscan be described as having a rectangular-wave shape or atrapezoidal-wave shape as opposed, for example, a triangle wave shape.Thus, the approximately rectangular or trapezoidal pleated filter mediumand edge treatments are particularly advantageous for third dimension orthickness (T) expansion/standing (from FIG. 5B to FIG. 6B) andreduction/flattening (FIG. 6B to FIG. 5B) without damaging thecomponents of the filter assembly.

In some alternate embodiments, for example, as shown in FIG. 8, filtermedium element 110 a can include rounded pleat shape channels 112 a(instead of rectangular shaped channels 112 as shown, for example, inFIG. 7). As illustrated in FIG. 8, in some embodiments, the collapsiblefilter assembly as disclosed herein can include filter medium element110 a having an original shape profile comprising a rounded pleat shapeby way of rounded pleat shape channels 112 a. The approximately roundedpleated filter medium and corresponding edge treatments are particularlyadvantageous for third dimension or thickness (T) expansion /standingand reduction/flattening without damaging the components of the filterassembly.

Conventional air filter pleat shapes are typically triangular, andconventional triangular pleat shapes are stable, strong, and resistantto collapsing; accordingly, when collapsed, convention triangular pleatshapes can suffer from a lack of controlled and repeatable collapse andrebound to their original shape. In contrast to conventional air filterwith triangular pleat shape, the present invention can include arectangular-wave shape, a trapezoidal-wave shape, or a rounded pleatshape wherein the respective pleat shape profile can encourage collapsein a controlled and repeatable manner.

It is noted that there is an additional configuration where the filteronly collapses in the thickness “T” dimension, in a similar method asdescribed here, in applications where it is unnecessary or undesirableto additionally reduce the filter in the “W” and “L” dimensions. In suchembodiments, the filter assembly 100 could be removed from productpackaging or other compressing constraint in the configuration of FIG.5A and then would be expanded to the configuration of FIG. 6A.

FIG. 7 is an exploded perspective view of the collapsible filterassembly so as to illustrate exemplary components, according to at leastone embodiment. As shown, the collapsible filter assembly has a topshell 130, the filter medium element 110, edge treatments 120, and abottom shell 140. The components of the filter assembly 100 are designedto align the engineered folds in the flattened configuration of FIG. 5Bto facilitate folding and unfolding.

The filter assembly 100 is referenced herein as a collapsible filterassembly 100 according to the rebound tendencies of the materials usedand according to the design, which includes, for example, therectangularly pleated filter medium element 110 and edge treatments 120.In other embodiments, the filter medium can have pleats that are square,trapezoidal, rounded, and/or saw-toothed. Upon removal of the filterassembly 100 from packaging and other restraints, the filter assembly100 naturally expands with regard to foot print and volume, with somemanual assistance being expected of a typical user in unfolding from thearea-reduced configuration of FIG. 1, to the area-expanded configurationof FIG. 5A, and to the volumetrically expanded configuration of FIG. 6A.It should be understood that the transitioning from a reducedconfiguration (FIG. 1) freed from packaging to an expanded configurationfor use (FIG. 6A) may depart from the stages and order of stepssuggested in considering the drawings as chronologically ordered (FIGS.1 through 6A). Some degree of unflattening (FIG. 5A to FIG. 6A) mayoccur even as the folded filter assembly 100 is removed. Each user maytreat the filter assembly 100 differently and thus each unpackaging anddeployment may progress with variations accordingly.

Whereas the figures illustrate a certain dimension of the pleat height,it is to be noted that there is no particular specific aspect ratiobetween pleat height and pleat width that is required for the inventionto operate as intended. Accordingly, in various embodiments, the aspectratio between pleat height and pleat width can be any suitable ratiovalues. For example, the aspect ratio between pleat height and pleatwidth can be 1:0.5, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1 or any othersimilar ratio values. Inventors have accordingly identified that whilethe shape of the pleat affects the effectiveness of the collapsiblefilter assembly to a considerable level, the aspect ratio between pleatheight and pleat width does not affect the effectiveness of thecollapsible filter assembly as much.

The top shell and bottom shell have matching footprints to form a framearound the filter medium element. In one embodiment, each shell haslinear outer edge strips 132 along the margins of the filter assembly100 and four sub-frame areas 134; each shell also includes four inneredge strips. In one embodiment, diagonally extending stringers 136 spaneach sub-frame area to stiffen the filter assembly 100 and support thefilter medium element across the otherwise open areas of the top shelland bottom shell; stringers 136 further operate to provide a degree ofprotection to the filter from mechanical damage.

The top shell and bottom shell are to be constructed of foldable andresilient materials to as to permit reduction and expansion and stillprovide structural support to the filter assembly 100 which may span,with or without additional external support, the interior flow channelof an air duct or other air-handling system interior space in use andunder the load of air pressure applied. The top shell and bottom shellmay be constructed of polymer, cardboard polyester, polymer and/orplastic. Cardboard or other durable paper or wood-fiber based productmay be used in some embodiments.

The edge treatments are constructed of resilient materials having somedegree of return force when flattened so as to naturally rebound orunfold to the heightened configuration of FIGS. 6A and 6B when releasedfrom the flattened configuration of FIGS. 5A and 5B. For example,plastic and/or spring steel may be used.

The filter medium element is generally porous and may be layered and mayinclude woven and non-woven materials such as paper, fabrics, piles,felts, mesh, and foams. The filter medium element may include materialsthat are melt blown, spun bound, carded, expanded, extruded or molded.The filter medium element may include materials having antimicrobial,olfactory, and/or chemical absorbent properties.

The product packaging 102 may be a box, bag, envelope or other containerand may be padded. The outer dimensions of the product packaging 102 maybe selected to conform to particular shipping and postage standards forconvenience and cost savings or for a particularly desired retail storepresence.

Further, in some embodiments, the collapsible filter assembly canfurther include a scrim layer or other similar stiff net-like materialcomprising a flat top layer and/or a flat bottom layer, with the filtermedium element being bounded by the flat top layer and/or the flatbottom layer of the scrim layer, for example. In some embodiments, thescrim layer can be configured to have a tensile disposition with bendingstiffness whereby the scrim encourages the pleats to rebound to anoriginal/expanded shape profile when in an expanded configuration.Accordingly, in various embodiments, the pleated filter medium elementcan be secured to one or more sheets of the scrim layer. The tensile andbending stiffness of the scrim layer can provide the ability of thepleats to rebound back to their original shape when the collapsiblefilter assembly is transferred from a collapsed configuration (as shown,for example, in FIG. 1) to an expanded configuration (as shown, forexample, in FIG. 5A). For example, a higher stiffness scrim layer can bebeneficial for pleat rebound. A stiff scrim layer can also provideadditional sturdiness to the filter and reduce deflection of the filterassembly when under load from airflow when in use. In some alternateembodiments, strips or supports can be reinforced and connected to theframe as an alternative to the scrim layer described above.

In some embodiments, the collapsible filter assembly can further includea frame wrap provided around the edges of the frame of a collapsiblefilter assembly. In various embodiments, the frame wrap around frameedges can encase, surround, or otherwise be attached to the frame of thecollapsible filter assembly. The frame wrap around frame edges can beused for functional purposes. For example, frame wrap around frame edgescan help seal the ends of the pleated portion of the filter;alternately, or in addition, the frame wrap around frame edges canprovide a more compliant surface to help achieve a better seal when thefilter assembly is installed in an HVAC register. The frame wrap aroundframe edges can also help provide a tight-fit to the register to assistinstallation, were the register holds the filter in place when closingthe grating. The frame wrap around frame edges can also prevent thefilter assembly from moving up and down when the flow of air is turnedon or off. In some embodiments, the frame wrap can have a geometry thatcreates an interference fit and further allows for collapse andexpansion for packaging, such as single-bend accordion-style geometry.In further embodiments, the frame wrap material can be stiff (forexample, the frame wrap material can comprise neoprene in oneembodiment) such that elements of the air filter assembly do not need tobe secured to each other at the corners. Accordingly, in variousembodiments, the frame wrap can be configured to seal the ends of thepleated portion of the filter. The frame wrap can also be configured toprovide a compliant surface to for a semi-seal to the register, and tofurther provide a compliant tight-fit to the register to assistinstallation.

In some embodiments, the frame wrap is configured to reduce noiseassociated with the filter moving when airflow is turned on or turnedoff. The partial seal created by the frame wrap as well as thedisruption to air flow resulting from the frame wrap can operate toreduce and even eliminate the whistling/noise otherwise generated whenairflow is turned on or turned off. Through experiments, the inventorshave discovered that the reduction in the noise or whistling isaccomplished by fabricating the frame wrap from a material that includessufficient loft such as, for example, felt, flannel, or a similar othermaterial. Through experiments, the inventors have also discovered thatthis benefit (i.e., the reduction in noise/whistling) is generally notobtained when the filter medium element is made up of a material such asa cotton sheet. Indeed, reduction of noise or whistling by the provisionof a frame wrap as discussed above is not limited to collapsible filterassemblies; in other words, reduction of noise or whistling by theprovision of a frame wrap as discussed above can also be obtained inconventional/existing non-collapsible filter assemblies that includecardboard frames, for example.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiments were chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

These and other changes can be made to the disclosure in light of theDetailed Description. While the above description describes certainembodiments of the disclosure, and describes the best mode contemplated,no matter how detailed the above appears in text, the teachings can bepracticed in many ways. Details of the system may vary considerably inits implementation details, while still being encompassed by the subjectmatter disclosed herein. As noted above, particular terminology usedwhen describing certain features or aspects of the disclosure should notbe taken to imply that the terminology is being redefined herein to berestricted to any specific characteristics, features, or aspects of thedisclosure with which that terminology is associated. In general, theterms used in the following claims should not be construed to limit thedisclosure to the specific embodiments disclosed in the specification,unless the above Detailed Description section explicitly defines suchterms. Accordingly, the actual scope of the disclosure encompasses notonly the disclosed embodiments, but also all equivalent ways ofpracticing or implementing the disclosure under the claims.

What is claimed is:
 1. A collapsible air-filter assembly comprising: afilter medium element; and a frame at least partially surrounding thefilter medium element, wherein the frame and filter medium element areconfigured to vary in at least one dimension by folding or unfolding. 2.The assembly of claim 1, wherein the frame comprises a top shell and abottom shell, and wherein the filter medium element is placed betweenthe top shell and bottom shell.
 3. The assembly of claim 1, wherein thefilter medium element is rectangular pleated or trapezoidal pleated. 4.The assembly of claim 1, wherein the filter medium element is pleated,wherein the pleats are generally rounded.
 5. The assembly of claim 1,wherein, in a configuration expanded by area and volume, the filtermedium element has rectangular channels extending from end to end. 6.The assembly of claim 5, further comprising edge treatments nestled withthe filter medium element.
 7. The assembly of claim 5, wherein channelsidewalls unfold upward from a flattened configuration to a standingconfiguration when the air-filter assembly is volumetrically expanded.8. The assembly of claim 1, wherein, when twice folded in twodimensions, the air-filter assembly is halved in length and halved inwidth.
 9. A variable filter assembly comprising: a filter mediumelement; and a frame at least partially surrounding the filter mediumelement, wherein the frame and filter media element are configured to bereducible in at least one dimension via a non-planar action, wherein thefilter medium element is pleated.
 10. The variable filter assemblyaccording to claim 9, wherein the pleats are generally rectangular. 11.The variable filter assembly according to claim 9, wherein the pleatsare generally trapezoidal.
 12. The variable filter assembly according toclaim 9, wherein the pleats are generally rounded.
 13. The variablefilter assembly according to claim 9, wherein edge treatments assist inexpansion of the pleats.
 14. The variable filter assembly according toclaim 9, further comprising a scrim layer extending approximatelyparallel to a major plane of the filter medium element and contactingthe filter medium element, wherein the scrim layer comprises a flat toplayer and bottom layer.
 15. The variable filter assembly according toclaim 14, wherein the scrim layer is configured to have a tensile andbending stiffness such that the pleats are encouraged to rebound to anoriginal shape profile in an expanded configuration of the variablefilter assembly.
 16. The variable filter assembly according to claim 9,further comprising a frame wrap surrounding edges of the frame.
 17. Thevariable filter assembly according to claim 16, wherein the frame wrapis configured to seal the ends of a pleated portion of the filter. 18.The variable filter assembly according to claim 16, wherein the framewrap is configured to reduce noise associated with the filter movingwhen airflow is turned on or off
 19. A collapsible air filter that: in acollapsed configuration is reduced in the dimension predominantlyparallel to the direction of air flow; in an expanded configuration isincreased in the dimension predominantly parallel to the direction ofair flow; and in switching from the collapsed configuration to theexpanded configuration, a series of pleats of a filter media of thecollapsible air filter is expanded thus increasing the effective filtermedia volume.
 20. A collapsible air filter according to claim 19,wherein a perforated or otherwise open sheet of resilient materiallaminated to the filter media assists in the expansion of the pleats.